Pedometer

ABSTRACT

An apparatus for measuring the distance covered by walking or running on foot, the apparatus comprising two complementary electronic devices, each fixed on one shoe. One of the devices, the slave unit, generates signals; the other device, the master unit, receives, stores and processes the signals to calculate speed and distance. Means for displaying the processed data are further provided.

CROSS-REFERENCES TO RELATED APPLICATIONS

This is the U.S. national phase filing, pursuant to 35 U.S.C. 371, ofPCT/IT97/00151.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to the measurement of the distancescovered and the speeds reached by walking and/or running people.

2. Description of the Related Art

As can be easily thought, to measure the distance covered by a personmoving on foot is a much more complex operation than that for measuringthe distance covered and the speed reached by vehicles moving on wheels.

Some electronic, commercially available devices for sportsmen are knownwhich are able to count the steps and to calculate, with greatapproximation, the distance covered.

With regard to this, it should be appreciated there is no problem incounting the steps but it is very difficult to determine the distanceand the speed at which the latter is covered. It is then evident thatthe length of the step, i.e. the distance between the two feet of thewalker, should be measured every time.

Such operation may be carried out in one of the following ways:

A) Transmission and reception of an ultrasonic signal by suitabletransducers measuring the time T taken by the signal and calculating thedistance S, the speed of sound being known (S=V×T; V=speed of sound).

B) Use of a radiofrequency system of very short range provided with atransmitter on one side and a receiver on the other side, both having adirectional antenna. Thus a signal directly proportional to the distanceis provided at the output of the receiver.

C) Measurement of a magnetic flow and detection of the distanceaccording to the amplitude (compass principle).

D) Use of a modulated infrared transmitting-receiving system providedwith an array of transmitting leds and receiving photodiodes so that thedetection of the signal is made directional and then proportional to thedistance.

In any case, whatever method is chosen, it is necessary to carry outsome automatic compensations which are able to keep the signal constantas the outer varying conditions change. It should be noted that suchchanges can also be varied along the same path. In order to betterexplain such aspect, in case the radiofrequency system is used, it issufficient to think to the difference between running on grass andrunning on reinforced concrete pavement. Actually, the reinforcement ofthe latter would cause an attenuation of the signal disturbing theoperation of the system.

It should be noted that all of the necessary detection operations haveto be synchronized with the positions of the feet (laid down or raised).

As far as the different methods mentioned above are concerned it shouldbe noted that system A) based on the use of ultrasounds has to bediscarded both because of the fragility of the transducers which cannotwithstand the mechanical stress in such an application and thedifficulty of protecting them from water splashes (rain, puddles, etc.).

System B) based on the use of radiofrequency signals has big applicationproblems because it requires calibrations and is particularly sensitiveto thermal variations. In order to overcome such problems it would benecessary to resort to a very expensive apparatus which would not berecommended for a commercial production.

The drawback of system C) using a magnetic flow consists in that it isstrongly depending on the type of pavement on which the user runs orwalks causing high variations of parameters and characteristics of thedetection system.

To sum up, the method involving fewer problems of the measurement anddisplay system is that of item D) above, i.e. that using an infraredtransmitting/receiving system.

BRIEF SUMMARY OF THE INVENTION

The present invention seeks to overcome the problems mentioned above byproviding a portable apparatus able to calculate with high precision thedistance covered and the speed.

The apparatus according to the invention essentially consists of twoseparate, complementary, electronic devices, one of which (slave) isable to transmit signals through suitable transmitting means, while theother (master) is able to receive said signals through suitablereceiving means and to store and to process them so as to calculate thedistance covered and the average and maximum speeds.

A better understanding of the invention will ensue from the followingdetailed description with reference to the annexed drawings which showby way of a not limiting example a preferred embodiment.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 is a block diagram of the slave device;

FIG. 2 is a schematic top plan view of the area swept by the infraredrays emitted by the slave;

FIG. 3 is a block diagram of the master;

FIG. 4 shows how the infrared rays emitted by the slave are received bythe master;

FIG. 5 is a diagram of the relation between detected signal anddistance;

FIG. 6 is a flow diagram of the way by which the apparatus is put in/outof stand-by condition;

FIG. 7 is a flow diagram of the slave;

FIG. 8 is a flow diagram of the master upon detecting thewalking/running;

FIG. 9A is a flow diagram of the master upon detecting and storing thedistance when walking in step;

FIG. 9B is a flow diagram of the master upon detecting and storing thedistance when running;

FIG. 10 is a flow diagram of the master upon displaying detected data.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF INVENTION

For the sake of simplicity of description the measurement and displaysystem is indicated at “FDM”, the left foot at “lf”, the right foot at“rf”, the data display system at “display”, and the infrared ray at“I.R.”.

It is important to note that, in case the apparatus is put within shoes,the construction and the design of FDM is made depend on that themechanical stress, to which the apparatus is subjected, causescomponents requiring calibration such as resistive and capacitivetrimmers as well as all of the components sensitive to mechanical shocksand vibrations to be avoided.

It should also be appreciated that sharp temperature variations canoccur (e.g. when the foot accidentally ends up into a water puddle withlower temperature). Therefore, the case of FDM should be watertight aswell as the outer portion of the sensors should not be affected and/ordamaged by even strong, and repeated water splashes.

In the present preferred embodiment the FDM consists of twocomplementary devices: “master” and “slave” supplied by cells anddescribed below in their basic components.

The master essentially includes:

1) A logic unit (CPU) consisting of a microcomputer capable ofmathematic calculations. The characteristics of such a componentprovide: a wide enough operating temperature range; a very low supplyvoltage (2-3 V); a very low stand-by power consumption (in the order offractions of microampere); an interface controlling a liquid crystaldisplay and provided with square wave generator; an analogue-to-digitalconverter for measuring the amplitude of the signal; a resolution of atleast 8 bits; a reference voltage generator stable with temperature; aceramic resonator oscillator (more rugged than crystal oscillator)having a frequency as near as possible the maximum allowable frequencyof microcomputer and resonator.

2) A liquid crystal display for displaying data relative to distancecovered, average speed, maximum speed, etc.

3) A pressure sensor for detecting the effective movement of the rightfoot, capable to synchronize the detection of the signal and toautomatically switch on/off the apparatus.

4) An array of sensors (I.R. receivers) preferably arranged in asemicircle surrounding the inner side of the right ankle within a casefor shielding them from sun's rays.

5) A filter selecting the infrared signal modulated at the output ofI.R. sensors.

6) A signal amplifier, the gain of which is such as not to saturate theanalogue-to-digital converter so as not to cause detection errors. Thismeans that the maximum value of the amplified signal is always lowerthan or equal to the maximum value allowable by CPU. Such amplifiershould have a good thermal stability and a very low power consumption(CMOS).

7) A sensor of the outer light for the automatic compensation of thesignal in different hours of the day or in case of sudden crossing ofdark places.

The slave essentially includes:

1) A pulse generator for supplying I.R. diodes.

2) A buffer current amplifier for controlling I.R. emitting diodes.

3) An array of I.R. emitting diodes preferably arranged in a semicirclesurrounding the inner side of the left ankle.

4) A pressure sensor for switching on/off the I.R. emitting diodes.

5) A logic unit (CPU) controlling the operation of the apparatus.

With reference to the figures mentioned above, the operation of theapparatus according to the invention will now be described.

Both units (master and slave) are provided with a self-switching on/offsystem so as to avoid any control by the user and at the same time tooptimize the cell consumption. This is accomplished by two pressuresensors SP which enable the respective unit as soon as a change of stateof the sensor occurs. The enabling condition of the units is kept untila change of state of the respective sensor SP is detected within apredetermined time-out.

Therefore, as soon as the feet move both master and slave units begintheir operations.

As far as the operation of the slave is concerned, any change of stateof the relative pressure sensor SP causes the slave unit to leave the“sleep” state (stand-by with the minimum power consumption).

At this time the time-out counting begins (FIG. 3), the latter being setto zero by any following change of state of pressure sensor SP, so thata signal consisting of a pulse succession amplified by the bufferamplifier is generated. Such a signal is fed to I.R. emitting diodes.

At this time a continues loop is provided, i.e. the I.R. emissioncarries on until the time-out procedure is started. In other words, ifno change of state is detected by pressure sensor SP before the end ofthe counting, the unit is switched off assuming the sleep state(stand-by) of minimum power consumption.

The operation of the master unit is different because pressure sensor SPhas a double function. Actually, in addition to cause the apparatus toleave the sleep state, such sensor synchronizes the time in which themodulated infrared signal from the slave is detected.

Also in this case the return of the apparatus to the sleep state (lowconsumption) occurs when no change of state is carried out by pressuresensor SP within a determined time-out.

In order to simplify FIGS. 9A and 9B the succession of changes of stateof pressure sensor SP is assumed to be free of time-out as accepted bythe system. It should be appreciated that the succession of footmovements is different according to the way of walking: going in step orrunning.

In the described preferred embodiment the slave unit is put in the leftshoe, while the master unit is put in the right shoe. In case ofmarching in step there is a succession of states which can berepresented as shown in the following table.

LF RF STATE I 0 0 STILL II 1 0 MOVEMENT III 0 1 MOVEMENT IV 0 0 STILL

The first state takes place at the beginning of the movement when thefeet are still and laid down.

The second state takes place when the left foot is raised to startwalking. At this time sensor pressure SP changes its state and causesthe slave unit to operate and to emit an infrared signal Which is keptalso when the foot is laid down again.

The third state takes place after the end of the step of the left footand the following raising of the right foot which causes the master unitto operate. Under such conditions the master unit operated by the changeof state of pressure sensor SP detects the I.R. signal and stores adigit according to the amplitude of the latter.

The master unit detects the signal at any change of state of itspressure sensor, i.e. both upon raising and laying down the right foot.

In case the reverse succession takes place, i.e. the right foot israised first, there are no problems because in this case the master unitis already operating when raising the left foot and then detects themodulated I.R. signal as soon as the slave unit starts the emission ofthe same.

The master unit processes then the amplitude of the I.R. (analogue)signal, converts it into a digital signal which is compared with areference voltage, and calculates a binary digit between 0 and 255. Themeasurement error is lower than 4/1000 (1/255=0.00392) of the maximumlength of the step.

Thus the obtained binary digit is stored in a register (FIGS. 9A and9B). The following detected values will be added up to the precedingvalues and, when the maximum capacity of the register is reached, thefollowing registers representing tens, hundreds, and thousands areincreased.

When the master unit returns to stand-by, data relative to the totaldistance covered, the average and maximum speeds are automaticallydisplayed. In order to perform such operations, the master unit comparesthe stored binary digits with a conversion table included in itsoperation program. Such data are stored in the memory and can beincreased by next movements or can be reset by a reset button.

In case the user is running, there is one more succession of states inthe table shown above. Actually it should be considered the situation inwhich both feet are raised. Moreover, the feet can rotate backwards uponrunning with the result of a masking of the I.R. signal. The master unitis able to evaluate whether the user is walking or running (FIG. 9) byonly detecting the succession and the frequency of the changes of stateof its pressure sensor. In such case, the signal measurement process isstarted in advance with respect to the time in which the right foot(where the master unit is installed) is laid down again. The amount ofsuch a time in advance is proportional to the speed and can change everymoment. Actually, the measurement is carried out before the foot rotatesbackwards. The same will take place before the foot is raised. Themeasurement of the signal is made in advance with respect to the time inwhich the right foot is raised from the ground. In other words, the timein advance in which the modulated I.R. signal is detected during the runis calculated by CPU according to the frequency of laying down/raisingthe foot to which the master unit is connected and depending on datastored in the memory and/or the program of CPU.

A second embodiment of the invention further provides a calculation ofthe calories consumed by the user along a predetermined path. As thecalorie consumption depends on the weight of the user, the distancecovered, and the speed at which such a distance has been covered, themaster unit also provides a weight sensor such as a load cell able toevaluate the weight of the user. The CPU of the master unit calculatesthe calories employed during the walking and/or the run by comparing thedetected weight, the distance covered, and the speed with its own datastored in the memory of the calculation program. Such beforehandobtained data (e.g. during experimentations) provide the calorieconsumption according to the weight and the parameters of themotor-action. In order to reduce the amount of such stored data and thenthe mass of the memory of the apparatus, it can also be provided analgorithm which calculates the calorie consumption by interpolating alower data amount.

The present invention is described and illustrated according to somepreferred embodiments thereof, however, it should be understood thatthose skilled in the art can make modifications and replacements withoutdeparting from the scope of the present industrial invention.

What is claimed is:
 1. An apparatus for measuring the distance covered by walking or running on foot adapted to be put within shoes or a portable case, comprising two separate, complementary electronic devices supplied by cells, wherein one of said devices is a slave unit fixed on one shoe and is capable of generating signals through suitable emitting means, while the other of said devices is a master unit fixed on another shoe, and is capable of receiving said signals through suitable receiving means, and of storing and processing said signals so as to convert said signals into a binary code, in so doing being capable of calculating a runner's or pedestrian's completed distance and average and maximum speeds, and automatically displaying the distance and speeds, said signals being modulated and directional so that the extent to which they are received by the master unit is proportional to the distance between the emitting and receiving means, wherein means for displaying the processed data are further provided.
 2. The apparatus of claim 1, wherein the emitting slave unit which is fixed on one shoe and the receiving master unit which is fixed on the other shoe, are provided with automatic self-switching means comprising logic units (CPU) activated by pressure sensors (SP), such that when a change of state of said sensors occurs, the apparatus is enabled for a predetermined length of time, after which the units automatically switch off, to avoid any control by the user and at the same time to minimize consumption of the power supply cells.
 3. The apparatus for measuring the distance covered by walking or running according to claim 1, wherein there are provided means for the conversion of the signal into a digital signal once received by the master unit and for its comparison with a reference voltage, a binary digit between 0 and 255 being obtained and stored in a register, said register adding it up to the values previously stored until when it has been filled, and other registers being provided to load the following binary digits, the data relative to the overall distance covered, to the average and maximum speed being automatically displayed immediately after the receiving master unit returns to stand by exactly when the runner or pedestrian stops running or walking, respectively.
 4. The apparatus for measuring the distance covered by walking or running according to claim 1, wherein the registers are in increasing order and represent units, tens, hundreds and thousands.
 5. The apparatus of claim 1, wherein said directional signals are modulated infrared rays.
 6. The apparatus of claim 1, wherein said emitting means are infrared transmitting leds and said receiving means are receiving photodiodes.
 7. The apparatus of claim 1, wherein the emitting slave unit comprises: a pulse generator feeding pulse signals to I.R. emitting leds; a buffer current amplifier for controlling the I.R. emitting leds; an array of I.R. emitting leds preferably arranged in a semicircle surrounding the inner side of the left ankle within a case; a pressure sensor (SP) capable to switch on/off the emission of I.R. rays; a logic unit (CPU) for controlling the operation of the apparatus; and the receiving master unit comprises: a logic unit (CPU) comprising a microcomputer capable of mathematic calculations and adapted to control a display; a liquid crystal display for displaying data relative to at least the parameters of distance covered, average speed, and maximum speed; a pressure sensor (SP) for detecting the effective movement of the right foot, capable to synchronize the detection of the signal and to automatically switch on/off the apparatus; an array of sensors comprising I.R. receivers arranged in a semicircle surrounding the inner side of the right ankle within a case for shielding them from sun's rays; a filter selecting the infrared signal modulated at the output of I.R. sensors; a signal amplifier, the gain of which is such that the maximum value of the amplified signal is always lower than or equal to the maximum value allowable by CPU so as not to saturate the analogue-to-digital converter and to avoid detection errors; a sensor of the outer light for the automatic compensation of the signal in different hours of the day or in case of sudden crossing of dark places.
 8. The apparatus of claim 1, wherein said logic unit (CPU) of the receiving master unit provides: a wide enough operating temperature range; a very low supply voltage of 2-3 V; a very low stand-by power consumption in the order of fractions of microampere; an interface controlling a liquid crystal display and provided with square wave generator; an analogue-to-digital converter for measuring the amplitude of the signal; a resolution of at least 8 bits; a reference voltage generator stable with temperature; a ceramic resonator oscillator more rugged than crystal oscillator having a frequency as near as possible the maximum allowable frequency of microcomputer and resonator.
 9. The apparatus of claim 1, wherein said amplifier has a good thermal stability and a very low power consumption (CMOS).
 10. The apparatus of claim 1, wherein the logic unit of the master unit is able to discriminate whether the user is walking or running from data detected by the pressure sensor, and in case the user is running, the detection of the signals received by the photodiodes is started in advance with respect to both the time in which the foot is laid down and the time in which the foot is raised.
 11. The apparatus of claim 10, wherein the amount of such a time in advance is calculated by the logic unit (CPU) of the receiving master unit by comparing the detected data with those stored in its control program.
 12. The apparatus of claim 1, wherein the receiving master unit further provides a weight sensor such as a load cell able to evaluate the weight of the user, the logic unit thereof having also a program for calculating the calorie consumption according to the weight, the distance covered, and the speed.
 13. The apparatus of claim 12, wherein the calculation of the calorie consumption is carried out by comparing the detected data with those stored in the calculation program. /
 14. The apparatus of claim 13, wherein said calculation program includes a data interpolation algorithm able to reduce the amount of stored data and then the request of memory in the logic unit. 